Despite a sustained Conservative attack that accuses him of pitting east against west, Thomas Mulcair refuses to back down from his assertion the unchecked development of the oil sands is responsible for the loss of hundreds of thousands of jobs in other sectors.

Heritage Minister James Moore demanded that the NDP Leader apologize to Western Canadians. He also pointed out that Mr. Mulcair has admitted to never visiting the Alberta oil sands.

"He should be ashamed of himself for attacking the West, dividing our country, and not even having visited the places he is attacking," Mr. Moore, who was standing in for the Prime Minister, said during Question Period Thursday. "It is unconscionable for someone who wants to be the prime minister of the country to be so utterly irresponsible."

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Mr. Mulcair, who if often accused of having a short fuse, has been keeping his emotions in check since winning leadership of the Official Opposition in March. But he met Mr. Moore's barbs with an angry response.

"Five hundred thousand good paying manufacturing jobs have been lost because we are not enforcing legislation," Mr. Mulcair shouted across the House of Commons. "We are allowing these [resource]companies to use the air, the soil and the water as an unlimited free dumping ground. Their model for development is Nigeria instead of Norway. We know what we want: It is sustainable development to protect future generations."

The verbal assault by Mr. Moore came the day after Saskatchewan Premier Brad Wall took to Twitter to condemn Mr. Mulcair's latest statements, including his accusations that Western premiers who lead conservative governments are merely "messengers" for Prime Minister Stephen Harper.

Alberta Premier Alison Redford has called Mr. Mulcair's comments "divisive and ill-informed." And British Columbia's Christy Clark has labelled his economic analysis "goofy."

The controversy has provided federal Conservatives with some needed fodder on the New Democrats, who have been rising in the polls since Mr. Mulcair was elected to succeed the late Jack Layton.

It started when Mr. Mulcair told a CBC radio program this month that the oil sands are artificially inflating the Canadian dollar and hollowing out the country's manufacturing sector – a phenomenon known as Dutch disease.

But that was not the first time Mr. Mulcair voiced his belief the economic ailment, created by oil companies that are not being forced to pay for the damages they are causing to the environment, is hurting Canada. He wrote an essay in March in Policy Options magazine explaining what he believes to be the correlation between the high Canadian dollar and the decline in Canada's forestry, fisheries and manufacturing sectors.

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A report by the Institute for Research on Public Policy published this week said, at best, Canada has a "mild case" of the disease.

But, after Question Period when he had taken some time to calm down, Mr. Mulcair said there is no denying the fact Canada is undergoing economic textbooks label Dutch disease.

The problem is not with development, he said. "It's how we're allowing the resource to be developed, without applying basic rules of sustainable development, without applying the one rule of sustainable development, which is polluter pay. If you don't include those costs, we're doing the same thing as if we had a factory where we were pushing the garbage into a river in the back. It's not the real profit, it's not the real price. That's driving the Canadian dollar up."

Mr. Mulcair said his fight is not with Western Canada or any premier. "My debate is right now in the House of Commons is with the government that's responsible for the legislation that's not being enforced."

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